Device for driving a vehicle and in particular a railway vehicle

ABSTRACT

An electric motor is placed around the axle of a vehicle but includes a rotor that does not contact the axle. A drive element is fastened to the axle and extends radially from the axle. The drive element for driving the axle is coaxially fastened to the axle but located laterally with respect to the electric motor. The rotor includes a disk that directly engages elements in a peripheral region of a drive element disk, the engagement occurring at a point remote from the axis of the axle.

FIELD OF THE INVENTION

The invention relates to a drive device for a vehicle and especially fora railroad vehicle. The invention also applies to the drive for roadvehicles.

BACKGROUND OF THE INVENTION

Vehicles, especially railroad vehicles, which comprise a structuremounted on at least one driving axle fitted with wheels which is drivenin rotation by an electric motor, such as a radial flux motor, areknown.

The motor, which is fixed to the structure of the vehicle and possiblysupported by the axle via a bearing, comprises a stator and a rotormounted so as to rotate with respect to the stator. The axle may bedriven in rotation by the rotor via gearwheels constituting a gearreducer. One of the gearwheels, which is fastened to the axle,constitutes a drive element extending radially around the axle and hastoothing which meshes with the pinion which may be fastened to therotor.

In such a drive device, the motor is inserted vertically between thevehicle structure and the axle, thereby requiring the vehicle structureto be placed at a certain height above the axle. Furthermore, the use ofa gear reducer has certain drawbacks, since it increases the overallsize of the drive device and has difficulty in absorbing the in-servicedisplacements between the vehicle structure and the axle.

It has been proposed to use drive devices for railroad or road vehiclescomprising an electric motor placed around the axle of the vehicle, orlocated in the central part of a wheel.

In the case of such drive devices, the rotor may be in direct engagementwith the axle or with the wheel. Direct driving of the axle or the wheelis generally performed by an internal part of the motor, generally by aninternal part of the rotor.

The rotor may also constitute part of the wheel.

In all cases, only a few possibilities for movement between the axle andthe drive motor remain.

In certain cases, the axle or wheel is driven via a gear reducer or adifferential but, in this case, the drawbacks mentioned above in thecase of railroad vehicles, whose drive device has a gear reducer, areagain found.

In the work “Histoire de la traction électrique (History of ElectricTraction)” volume 1, chapter IX, pages 373-395, by Machefert Tssin etal., électrique (History of Electric Traction)” volume 1, chapter IX,pages 373-395, by Machefert Tssin et al., La vie du rail (Rail Life),Paris 1980, there is description of gearless transmissions providing theelectric traction of a railroad vehicle, based on a motor whose armaturemay be mounted on a hollow shaft allowing passage and movement of anaxle of the vehicle and drives at least one wheel of the vehicle via acompliant transmission.

FR-A-550836 describes a device for driving a vehicle along rails,comprising an electric motor mounted around an axle of the vehicle withthe possibility of movement of the axle, the rotor of the motor beingmounted on a first hollow shaft and driving the axle in rotation via thefirst and second hollow shafts, through which the axle passes, and viatwo universal joints.

BRIEF DESCRIPTION OF THE INVENTION

It is therefore an object of the invention to provide a device fordriving a vehicle comprising a structure mounted on at least one drivingaxle fitted with wheels, which includes at least one electric motorsupported by the structure of the vehicle and having a stator and arotor mounted so as to rotate with respect to the stator, placed aroundthe axle but not in contact with the axle, and a drive element fastenedto the axle extending radially from the axle, this device allowing thevehicle to be driven very satisfactorily, with the possibility ofmovement between the axle and the motor.

For this purpose, the element for driving the axle is located laterallywith respect to the electric motor, along the axial direction of theaxle, and the rotor is fastened to drive means designed to engagedirectly with the element for driving the axle in rotation.

In order to make the invention clearly understood, a drive deviceaccording to the prior art and a drive device according to the inventionand according to several embodiments will now be described by way ofexample.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 a schematic end view in partial cross section of a drive deviceaccording to the prior art.

FIG. 2 is an end view in partial cross section of a drive deviceaccording to the invention in a first embodiment.

FIG. 3 is an end view in partial cross section of a device according tothe invention in a second embodiment.

FIG. 4 is an end view in partial cross section of a drive deviceaccording to the invention in a third embodiment.

FIG. 1 shows a prior art device for driving a railroad vehicle whichcomprises an axle 1 on which wheels 3 designed to move along rails 4 aremounted.

DETAILED DESCRIPTION OF THE FIGURES

The axle 1 is fixed beneath the structure 2 of the railroad vehicle bymeans of Known suspension elements (not shown in the figure).

The drive device comprises a radial flux electric motor 6 which is fixedto the structure 2 of the vehicle by known fixing means 5 and which issupported via a bearing 8 by the axle 1 of the vehicle. The axle 1 isfastened to a gearwheel 10 which is placed around the axle and whichextends radially around the axle. The gearwheel 10 has toothing on itsperipheral surface which meshes with a pinion 9 fastened to the shaft 7of the motor 6. Use of a drive device as shown in FIG. 1 means that thestructure 2 of the vehicle must be located a substantial distance abovethe axle 1, in order to be able to house the motor 6 and the gearreducer consisting of the gearwheels 9 and 10. In addition, the assemblyconsisting of the motor and the gear reducer rests partially on theaxle, so that the displacements and vibrations of the axle aretransmitted to the gear reducer and to the motor.

FIGS. 2, 3 and 4 show a drive device according to the invention inseveral embodiments. The corresponding elements in FIGS. 2, 3 and 4 havebeen assigned the same reference numbers.

FIG. 2 relates to a first embodiment of a drive device according to theinvention used for driving a railroad vehicle, which is denoted overallby the reference number 10. This figure shows the structure 12 of therailroad vehicle and an axle 13 fastened to wheels 11 intended to movealong rails 14.

The structure 12 of the vehicle is connected to the axle 13 viacompliant supports 15 in which the axle 13 is mounted so as to rotatevia bearings 16.

The drive device 10 comprises an electric motor 17 placed around theaxle and a drive element 18 consisting of a disk fastened to the axleand located laterally with respect to the motor 17.

The motor 17 is a disk-type motor which comprises a stator 19 and arotor 20 mounted so as to rotate inside the stator via bearings 21 and21′.

The stator and the rotor are symmetrical bodies of revolution and havemeridional sections which can be seen in FIG. 2.

The stator 19 is in the form of a disk 22 fastened at its periphery to ashell 23 by means of which the stator and the entire motor 17 aresuspended from the structure 12 of the vehicle via support elements 24.

The disk 22 of the stator carries, on each of its faces, windings whichgenerate a rotating magnetic field of axial direction, that is to saydirected along the axis 25 common to the motor 17 and to the axle 13.

The rotor 20 comprises two rotor disks 26 and 26′ located on each sideof the stator disk 22, which disks carry windings or permanent magnetson their faces opposite those faces of the stator disk 22 which carrythe windings.

The rotor may be made in two parts joined together along the junctionzone 27.

The internal part of the rotor is made in the form of a shell 28, theinside diameter of which is greater than the diameter of the axle 13.Because of the presence of a radial clearance between the axle 13 andthe internal part of the motor 17 consisting of the shell 28 of therotor, the motor 17, suspended from the structure 12 of the vehicle, isnot in contact with the axle, which can have a certain movement withinthe structure of the motor when the vehicle is running along the rails14.

The disk 26 of the rotor 20 constitutes, on that lateral side of themotor which is located opposite the drive disk 18 fastened to the axle,the male part of a dog coupling, the dogs 29 of which, projectingoutward from the motor axially, are engaged in radially directed notches(or toothing) 30 machined in the periphery of the disk 18. The dogcoupling, consisting of the dogs 29 and the notches 30 in the disk 18,which provides a direct coupling link between the rotor and the disk 18fastened to the axle 13, may, however, include a damping system orabsorbing the accelerations transmitted to the axle by the rotor 20 orthe wheels 11 running along the rails 14.

Because the torque is transmitted by the rotor 20 to the axle 13 in aregion of the disk 18 radially remote from the axis 25 of the axle,transmission of the torque is improved. In addition, a coupling such asa dog coupling ensures that there is both very good transmission of thetorque and a certain movement in the radial direction of the axle.

The motor 17 may be made in an entirely closed form, as shown in FIG. 2,the shell 23 of the stator closing the motor around the outside, theshell 28 of the rotor closing the motor around the inside andcomplementary closure elements 31 and 31′ practically closing off thespace between the stator or the rotor, in which space the rollingbearings 21 and 21′ are located.

This closed construction of the motor has an advantage if the vehiclehas to run along polluted tracks.

In addition, the motor may include a commutator cooling circuit 32 and32′ which makes it possible, at startup, to remove any ice from themotor. To do this, a preheated fluid is made to circulate within thecooling circuit.

FIG. 3 shows a second embodiment of a drive device according to theinvention, used for driving a railroad vehicle comprising a vehiclestructure 12 and an axle 13 driven by the drive device denoted overallby the reference number 40. The corresponding elements in FIGS. 2 and 3are denoted by the same reference numbers.

The drive device 40 according to the embodiment shown in FIG. 3comprises an electric motor 33 and the drive disk 18 fastened to theaxle 13 located laterally, along the axis 25 of the axle 13, withrespect to the motor 33.

The embodiment of the drive device shown in FIG. 3 differs from theembodiment shown in FIG. 2 only by the construction of the electricmotor 33.

The motor 33 consists of two assemblies 34 and 35 each produced in asimilar manner to the electric motor 17 of the first embodiment shown inFIG. 2 and placed in series along the axis 25 common to the axle and tothe motor 33.

Each of the assemblies 34 and 35 has a stator part and a rotor part,these being substantially analogous to the stator and rotor of the motor17 of the first embodiment.

Each of the stator parts comprises a stator disk, windings generating arotating magnetic field being placed on each of the faces of said statordisk, and an external shell fastened to the peripheral Dart of thestator disk.

The external shells of the stator parts of the assemblies 34 and 35 arebutted together in a junction zone 37, in order to form the externalshell 36 of the motor 40, by means of which shell the motor is suspendedvia suspension elements 38 from the structure 12 of the railroadvehicle. The rotor parts of the assemblies 34 and 35 consist of

three elements butted together along the axis 25 common to the motor andto the axle 13, the central element, which is connected to the endelements in regions 39 and 39′, being common to the rotor part of theassembly 34 and to the rotor part of the assembly 35. The rotor of themotor 40 comprises, in its entirety, an internal shell 41 and threerotor disks, the faces of which are placed opposite those faces of thestator disks which are provided with windings. The faces of the rotordisks opposite the faces of the stator disks carry windings or permanentmagnets.

The rotor is mounted so as to rotate inside the stator shell 36 viabearings 42 and 42′.

The shell 41 of the rotor has an inside diameter greater than thediameter of the axle 13 so that there is a radial clearance between theaxle 13 and the shell of the rotor, allowing movement of the axle 13with respect to the motor 40 while the railroad vehicle is travelling.

The drive disk 18 fastened to the axle 13 is located laterally withrespect to the motor 40, along the axis 25 of the motor and of the axle,on the same side as the assembly 34. The drive disk 18 has, in itsperipheral part, notches or drive toothing in which dogs 43 fastened tothe rotor of the motor 40 are engaged.

As in the case of the embodiment shown in FIG. 2, the dog coupling,consisting of the dogs 43 and the peripheral part of the disk 18,constitutes a directly coupled transmission between the rotor of themotor 40 and the axle 13.

The region where the forces are transmitted Is also shifted a certainradial distance away from the axis 25 common to the motor and the axle.The dog transmission also allows a certain radial movement between thedrive disk 18 fastened to the axle and the motor suspended from thestructure 12 of the motor vehicle.

In the case of the drive device according to the first embodiment shownin FIG. 2 or in the case of the second embodiment shown in FIG. 3, thedrive disk 18 may be placed laterally, on one side of the motor or theother, or else a drive disk may be placed each side of the motor, therotor of the motor having, in this case, direct drive parts such as dogsat each of its axial ends.

The construction of a motor such as the motor 40 from several modularassemblies allows motors of different power to be assembled from moduleswhich may be identical.

As shown in FIG. 3, the motor 40 comprising two assemblies 34 and 35 maybe produced in a completely closed form, just like the motor 17 of thefirst embodiment.

FIG. 4 shows a third embodiment of the drive device according to theinvention applied to driving a railroad vehicle having a vehiclestructure and at least one driving axle.

In the case of the drive devices according to the First and secondembodiments, the electric drive motor 17 or 40 is a disk motor.

The drive device according to the third embodiment, shown in FIG. 4,differs from the first and second embodiments only by the constructionof the drive motor 45 which is a motor of cylindrical structure.

The motor 45 is produced and placed so as to lie around the axle 13,without any contact with the axle. The motor 45 of cylindrical structurecomprises a stator 46 and a rotor 48 mounted so as to rotate in thestator, about the axis 25 common to the axle and to the motor, viabearings 47 and 47′.

The stator 46, which has a cylindrical annular shape, is suspended fromthe structure 12 of the railroad vehicle via fixing elements 49 and 49′connected to the cylindrical lateral surface of the stator 46. The rotor48 is in the form of a cylindrical shell fastened, at one of its ends,to an annular disk 48′.

The stator 46 carries, on its cylindrical internal surface, windings 44which generate a magnetic field rotating around the axis 25 of themotor. The rotor 48 carries, on the external surface of its cylindricalpart, windings or permanent magnets 50 opposite the windings 44 of thestator. The cylindrical part of the rotor 48 has an inside diametergreater than the diameter of the axle 13 so that there is a radialclearance between the external surface of the axle and the internalsurface of the rotor.

The disk-shaped end Dart 48′ of the stator carries drive dogs 51 whichengage in notches or in toothing of the peripheral part of the drivedisk 18. Thus, the disk 18 and the axle are driven directly by the rotor48. However, as in the case of the first and second embodiments, the dogcoupling, consisting of the dogs 51 and the peripheral part of the driveelement 18, may be combined with a damping system making t possible toabsorb the drive forces and to avoid jolts during accelerations ordecelerations of the railroad vehicle.

As in the case of the first and second embodiments, the transmission ofthe forces is shifted a certain radial distance from the axis 25 of theaxle and movement between the axle and the motor is possible despite thedogs of the dog coupling meshing in the notches for accommodating thedogs of the peripheral part of the drive disk 18.

The drive device according to the invention firstly has the advantagesobtained in all the cases in which a motor placed around the axle isused, this arrangement of the motor making it possible, in particular,to bring the structure of the vehicle closer to the axle and thereforeto lower the vehicle and increase its stabilty during use. In order toobtain the most compact arrangement possible, an electric motor is usedwhose overall outside diameter is less than the diameter of the wheelsof the vehicle. In this case, the motor is entirely housed within thewheel train.

The electric motor of the drive device according to the invention isentirely suspended from the structure of the vehicle. This makes itpossible to improve the traction performance of the drive device and tolimit the transmission of vibrations, because the axle is not in contactwith the motor.

The forces are transmitted at a certain radial distance from the axis ofthe axle, which distance can be optimized by choosing the dimensions ofthe disk or other drive element fastened to the axle.

Furthermore, because there is a clearance between the rotor and the axleand because a coupling having a certain freedom of radial movement isused, the axle is virtually free with respect to the drive motor.

The invention is not limited to the embodiments that have beendescribed.

Direct coupling of the drive element fastened to the axle via the rotormay be achieved laterally, on one side of the motor or the other, or onboth sides. In the case of a dog coupling, the dogs may be fastened to apart of the disk-shaped rotor which is placed at least at one of theaxial ends of the motor.

The electric motor, when it is of the disk type, may have two or morestator disks and three or more rotor disks, these being arranged so thateach stator disk is inserted, in the axial direction of the motor,between two rotor disks.

Instead of a single motor or a single motor assembly, several motors orseveral motor assemblies may be used, the rotors of which each ensuredirectly-coupled transmission of a drive torque to a drive elementfastened to the axle. In this case, it is possible to use all the motorsor motor assemblies at the same time or, optionally, only certain ofthese motors or motor assemblies.

The motor or motors or motor assemblies may be placed in arrangementswhich are centered or are symmetrical along the axial direction of theaxle, or else in off-center or nonsymmetrical arrangements.

When the motor is of the disk type, it comprises in general at least onestator disk and one rotor disk having opposing faces, a plurality ofelectrical windings being fixed to the face of the stator disk and aplurality of windings or Permanent magnets being fixed to the opposingface of the rotor disk.

The coupling between the rotor and the element for driving the axle maybe produced not only in the form of a dog coupling but also in any otherform, such as a disk coupling. In all cases, the coupling between therotor and the drive element must be a direct coupling allowing a certainmovement perpendicular to the axis of the axle.

The drive device according to the invention can be applied not only tothe driving of railroad vehicles but also in the case of road vehiclesor all-terrain vehicles.

What is claimed is:
 1. A device for driving a vehicle mounted on atleast one driving axle fitted with wheels, the device comprising: atleast one electric motor having a stator and a rotor mounted so as torotate with respect to the stator, the rotor placed around the axle butnot in contact with the axle; a drive element fastened to the axle andextending radially from the axle; the drive element being a drive diskcoaxially fastened to the axle and located laterally with respect to theelectric motor, along the axial direction of the axle, the drive elementdriving the axle; the motor having at least one stator disk and at leastone rotor disk, the rotor disk and stator disk having opposing faces; aplurality of electrical windings being fixed to the face of the statordisk; a plurality of windings or permanent magnets being fixed to theopposing face of the rotor disk; and the rotor disk fastened to meansfor directly engaging elements in a peripheral region of the drive disk,remote from an axis of the axle.
 2. The device as claimed in claim 1,wherein the direct engaging means comprises dogs which project outwardlyfrom the motor in the axial direction, and the engaging elements arenotches formed in the peripheral region of the drive disk, the dogs ofthe rotor and the peripheral part of the drive disk constituting a dogcoupling having movement in the radial direction.
 3. The device asclaimed in claim 2, wherein a damping system is combined with the dogcoupling so as to avoid jolts during acceleration or deceleration of thevehicle.
 4. The device as claimed in claim 1, wherein the stator of theelectric motor includes a stator disk carrying electrical windings oneach of its faces; and further wherein the rotor of the motor includestwo rotor disks placed on either side of the stator disk, each rotordisk having, on one of its faces opposing a face of the stator disk,windings or permanent magnets.
 5. The device as claimed in claim 1,wherein the stator of the electric motor includes at least two statordisks provided with electrical windings on their faces and the rotor ofthe motor includes at least three rotor disks arranged so that a statordisk is inserted, along the axial direction of a motor, between twoadjacent rotor disks, the rotor disks having permanent magnets on theirfaces opposing the faces of the stator disks.
 6. The devices claimed inclaim 1, wherein the dogs are fastened to at least one rotor disk placedat one axial end of the motor.
 7. The devices claimed in claim 1,wherein the rotor of the motor engages with the element for driving theaxle via a disk coupling.